TRENTON, N.J. - For the first time, it appears that more than half of all insured Americans regularly take prescription medicines for chronic health problems, a study shows.

The most widely used drugs are those to lower high blood pressure and cholesterol -- problems often related to heart disease, obesity and diabetes.

The numbers were gathered last year by Medco Health Solutions, which manages prescription benefits for about one in five Americans.

Experts say the data reflect worsening public health, better medicines for chronic conditions and more aggressive treatment by doctors.

More people are taking blood pressure and cholesterol-lowering medicines because they need them, said Dr. Daniel W. Jones, president of the American Heart Association.

Americans buy more medicine per person than any other country. But it was unclear how their prescriptions compare with those of insured people elsewhere. Comparable data were not available for Europe, for instance.

Medco's data show that last year, 51 percent of U.S. children and adults were taking one or more prescription drugs for a chronic condition, up from 50 percent in the previous four years and 47 percent in 2001. Most of the drugs are taken daily, although some are needed less often.

The company examined prescription records from 2001 to 2007 of a representative sample of 2.5 million customers, from newborns to the elderly.

Drug use for chronic problems was seen in all demographic groups:

* Almost two-thirds of women 20 and older.

* One in four children and teens.

* Fifty-two percent of adult men.

* Three of four people 65 or older.

Among seniors, 28 percent of women and nearly 22 percent of men take five or more medicines regularly.

One couple, many meds

Karen Walker of Paterson, N.J., takes 18 prescription medicines daily for high blood pressure, diabetes, chronic back and shoulder pain, asthma and the painful muscle disorder fibromyalgia.

"The only way I can do it and keep my sanity ... is I use pill boxes" to organize pills for each morning and night, said Walker, 57, who works full time as a nurse at an HIV clinic.

Walker's 69-year-old husband, Charles, keeps his medicines lined up on his bureau: four pills for arthritis and heart disease, plus two inhalers for lung problems.

Dr. Robert Epstein, chief medical officer at Medco, which is based in Franklin Lakes, N.J., said he sees bad news and good in the findings.

"Honestly, a lot of it is related to obesity," Epstein said. "We've become a couch potato culture, (and) it's a lot easier to pop a pill" than to exercise regularly or watch your diet.

On the good side, he said, researchers have turned what used to be fatal diseases into chronic ones, including AIDS, some cancers, hemophilia and sickle-cell disease.